Splice-on optical connector for outside plant drop cable

ABSTRACT

A connector assembly for a fiber optic cable comprises a multi-part inner housing adapted to support an optical fiber splice connection structure. A cable clamp is located at a proximal end of the inner housing and is adapted to engage an outer sheath of a fiber optic cable. Preferably, the cable clamp is rotatable with respect to the inner housing.

This application is based upon and claims priority to U.S. ProvisionalPatent Application No. 61/918,814, filed Dec. 20, 2013 in the UnitedStates Patent and Trademark Office, and is a U.S. national stage filingof International Application No. PCT/US2014/071929 having aninternational filing date of Dec. 22, 2014, the disclosures of both ofwhich are incorporated by reference herein in their entireties.

BACKGROUND OF THE INVENTION

The present invention relates generally to fiber optic cable. Moreparticularly, the present invention relates to a splice-on opticalconnector for terminating outside plant drop cable or other opticalfiber cable.

The ability of high-quality optical fiber to transmit large amounts ofinformation without appreciable signal degradation is well known. As aresult, optical fibers have found widespread use in many applications,such as voice and data transmission. Optical fiber is typically suppliedand installed as fiber optic cable. The term “fiber optic cable” refersto the combination of the actual optical fiber plus the structure inwhich it is carried and protected during and after installation.Generally, a fiber optic cable includes the optical fiber, aramid fibersor other strength members, and an outer sheath. One common type of fiberoptic cable used as outside plant drop cable is “flat type cable.”Because flat type cable typically has two strength members of aramidfiber reinforced polymer (FRP) located on lateral sides of the opticalfiber, it exhibits sufficient stiffness for use as a drop cable.

In this application, current assembly technology uses factory terminatedoptical connectors. As a result, specific cable lengths are built forvarious deployments and excess cable is stored on site. While splice onconnectors for optical fiber cables exist, they are not available fordirect connection to flat drop outside plant cable. A splice-onconnector would allow the flat drop outside plant cable to be fieldinstalled and the cable cut to the length required.

The present invention recognizes the foregoing considerations, andothers, of the prior art.

SUMMARY OF THE INVENTION

According to one aspect, the present invention provides a connectorassembly for a fiber optic cable. The connector assembly comprises amulti-part inner housing adapted to support an optical fiber spliceconnection structure. A cable clamp is located at a proximal end of theinner housing and is adapted to engage an outer sheath of a fiber opticcable. Preferably, the cable clamp is rotatable with respect to theinner housing.

In some exemplary embodiments, the cable clamp has at least one beamwhich presses against the outer sheath of the fiber optic cable. In thisregard, the beam(s) may define a plurality of gripping structures (suchas “teeth”) on an inside surface thereof. The beam(s) may also define aramp which is moved into engagement with the fiber optic cable by acomplementary ramp on a clamp ring. Preferably, the clamp ring may beconfigured to be moved axially into interlocking engagement with thecable clamp while urging the at east one beam into engagement with thefiber optic cable.

It will often be desirable for the cable clamp to define an axial slotfor receipt of the fiber optic cable. In addition, the cable clamp maybe axially movable with respect to the inner housing over a limitedaxial extent. The cable clamp may include first and second spaced-apartflanges which limit the axial movement of the cable clamp with respectto the inner housing.

The optical splice connection structure may include a splice protectionsleeve having an optical connector ferrule located at one end thereof.In this regard, the inner housing may define an elongate stem at adistal end thereof configured to support the protection sleeve. In someexemplary embodiments, the inner housing may comprise two semicircularhalves which mate together. Moreover, an outer boot may be received overa portion of the inner housing, the cable clamp being contained in theouter boot. The outer boot in some embodiments may comprise aninwardly-directed projection which limits rotation of the cable clampwith respect to the inner housing to a predetermined angular extent.

Another aspect of the present invention provides a connector assemblyfor a fiber optic cable. The connector assembly comprises an innerhousing having an elongate stem at a distal end thereof, the elongatestem configured to support a protection sleeve of an optical fibersplice connection structure. A cable clamp, located at a proximal end ofthe inner housing, is rotatable with respect to the inner housing. Theconnector assembly further includes a clamping element adapted to bemoved axially into interlocking engagement with the cable clamp totighten the cable clamp with respect to the fiber optic cable.

According to a still further aspect, the present invention provides aconnector assembly for a fiber optic cable. The connector assemblycomprises an inner housing having an elongate stem at a distal endthereof, the elongate stem configured to support a protection sleeve ofan optical fiber splice connection structure. A cable clamp, located ata proximal end of the inner housing, is being axially movable withrespect to the inner housing over a limited axial extent. The connectorassembly further includes a clamping element adapted to be moved axiallyinto interlocking engagement with the cable clamp to tighten the cableclamp with respect to the fiber optic cable.

Another aspect of the present invention involves a method of attaching afiber optic connector. According to one step of the method, an opticalfiber cable is prepared for attachment of the connector includingexposing a predetermined length of optical fiber. According to anotherstep, a splice protection sleeve and connector ferrule is attached to adistal end of the optical fiber. A cable clamp is fixed on the fiberoptic cable at a location spaced apart from the splice protection sleeveand ferrule. According to another step of the method, a multi-part innerhousing is assembled around the optical fiber so as to support theprotection sleeve and retain the cable clamp, the cable clamp beingrotatable with respect to the inner housing. An outer boot is moved intoposition such that a portion of the inner housing is received in theouter boot and the cable clamp is fully contained in the outer boot.

Other objects, features and aspects of the present invention areprovided by various combinations and subcombinations of the disclosedelements, as well as methods of practicing same, which are discussed ingreater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, to one of ordinary skill in the art, is set forthmore particularly in the remainder of the specification, includingreference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a splice-on connector assembly inaccordance with an embodiment of the present invention.

FIG. 2 is a perspective view of the splice-on connector assembly of FIG.1 from a different viewing angle.

FIG. 3 is a rear perspective view of the splice-on connector assembly ofFIG. 1 showing rotation of the cable.

FIG. 4A is a partially assembled view showing components of thesplice-on connector assembly of FIG. 1.

FIG. 4B is a partial cross-sectional view showing components of thesplice-on connector assembly of FIG. 1.

FIGS. 5A-5I illustrate various steps in the process of assembling thesplice-on connector of FIG. 1 to a flat drop outside plant cable.

Repeat use of reference characters in the present specification anddrawings is intended to represent same or analogous features or elementsof the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

It is to be understood by one of ordinary skill in the art that thepresent discussion is a description of exemplary embodiments only, andis not intended as limiting the broader aspects of the presentinvention, which broader aspects are embodied in the exemplaryconstructions.

FIGS. 1 and 2 illustrate an assembled splice-on connector assembly 10 inaccordance with an embodiment of the present invention attached to aflat drop cable 12. Generally speaking, connector assembly 10 comprisesa plug portion 14 and a support structure 16. As one skilled in the artwill appreciate, plug portion 14 is configured to mate withcomplementary optical sockets. The support structure 16 supports theplug portion and the protection sleeve (where the actual splice iscontained), while also being attached to the cable 12. As will beexplained, this arrangement provides sufficient retention as to preventthe cable from separating from the connector. As shown in FIG. 3,support structure 16 preferably allows rotation of the cable 12 withrespect to plug portion 14 (e.g., up to 300 degrees in this example). Inthis regard, flat drop cables have preferential bending directions dueto the lateral strength (or tension) members. Allowing the connector toswivel in this manner provides an adjustment to align the connector withthe socket and prevents imposition of torque at the plug-socketinterface due to the cable.

Referring now to FIGS. 4A and 4B, certain additional details regardingconnector assembly 10 can be explained. As can be seen, connectorassembly 10 includes an elongate inner housing 18 formed of twosemicircular halves. In the ensuing discussion, this inner housing willbe referred to as a “stop ring.” The two halves preferably havecomplementary mating features, such as post 20 and receptacle 22, tofacilitate alignment. The distal end portion of stop ring 18 is formedas a rigid stem to support the splice protection sleeve (fusion sleeve)24, flange 26, and ferrule 28. In this embodiment, ferrule 28 isspring-loaded by a coil spring 29 located between flange 26 and anopposing face of the stop ring stem. When the two halves of stop ring 18are assembled, a plug frame 30 is received over the end of the rigidstem. In addition, a retainer sleeve 32 (FIG. 1) may be received overthe plug frame and rigid stem, as shown.

As can be seen in FIG. 4B, a length of jacketed optical fiber extendsbetween cable 12 and sleeve 24 inside a hollow region 34 of stop ring18. In this case, for example, the optical fiber is shown as 250 μmoptical fiber. As will be apparent from the discussion below, thisarrangement provides flexibility which allows the optical fiber to moveduring attachment of the plug to a socket.

In this embodiment, support structure 16 includes a cable clamp 36 and aclamp ring 38 by which it is attached to cable 12. As shown, cable clamp36 includes a configured slot in which an end portion of cable 12 isreceived. Cable clamp 36 further includes a pair of beams (here in theform of ramps 40) which engage the outer sheath of cable 12 when clampring 38 is moved into position. The inside faces of ramps 40 preferablydefine teeth or other suitable structure to firmly grip the sheath ofcable 12. It will be appreciated that clamp ring 38 preferably definescomplementary ramps that cause the teeth of ramps 40 to squeeze thesheath. To prevent subsequent separation between cable clamp 36 andclamp ring 38, the outer faces of ramps 40 and the inner surfaces of theclamp ring ramps preferably define complementary ratcheting structuresto interlock cable clamp 36 and clamp ring 38. Moreover, as greaterforce is applied to pulling the cable, the tighter the cable clampbecomes.

Cable clamp 36 further includes annular flanges (or stops 41 and 42)which engage an annular lip 43 of stop ring 18. This limits the axialextent that cable 12 can move with respect to the support structure. Inaddition, cable clamp 12 further includes an axial key 44 whichfacilitates assembly of the connector assembly (e.g., positioning of theplug frame 30). In addition, key 44 may serve as a rotational stop tolimit the angular movement of cable 12 with respect to the connectorassembly.

A preferred manner by which connector assembly 10 may be assembled willnow be described with reference to the remaining Figures. First, asshown in FIG. 5A, a length of jacketed optical fiber is exposed byremoving a portion of the surrounding structure such as the outer sheath(referred to as “black jacket” in the drawing). Note that short lengthsof the lateral strengthening members 45 extend beyond the outer sheathin this illustration.

The exposed optical fiber 46 is then stripped, cleaned and cleaved toprepare it for splicing. Next, the prepared optical fiber is spliced tothe other side of the ferrule fiber. The resulting splice point iscontained and protected within the protection sleeve, as shown in FIG.5B.

Referring now to FIGS. 5C-5E, the cable is set into the slot of cableclamp 36. In this embodiment, the outer sheath is not received in theslot, but juxtaposes stop 42. The short lengths of exposed strengtheningmembers 45, however, are received in the slot. Next, clamp ring 38, isslid along cable 12 into engagement with cable clamp 36. This causesramps 40 to firmly engage the sheath such that the connector assembly isattached to cable 12. The optical fiber is not damaged, however, becauseit is protected from itself being squeezed by the strengthening members45.

Additional assembly steps are shown in FIGS. 5F-5I. After the protectionsleeve, ferrule and spring are set into one part of the stop ring, theother part is positioned to complete the stop ring 18. The key 44 of thecable clamp may then be moved into a corresponding slot on the stop ringto move the plug frame 30 into position. It will be appreciated thatthis causes the fiber inside the hollow portion of the stop ring 18 tobend. Thus, once the plug frame 30 is in place, the key 44 may be movedout of the slot to release this bending. This also allows the cable torotate with respect to the support structure over a limited angularrange as discussed above. The retainer sleeve 32 may also be positionedover the plug frame and rigid stem of the stop ring.

Finally, outer boot 48 may be snapped into position (see FIGS. 1-3) inorder to cover cable clamp 36 and clamp ring 38. In this regard, thestop ring may define flexible arms (such as arm 50 in FIG. 4A) havingoutwardly directed projections at their distal ends. The arms flexinward to allow boot 48 to be moved into position. But when boot 48 isin position, the projections are received in corresponding apertures 49in boot 48. Preferably, boot 48 may define an inwardly directedprojection 52 which engages key 44 if cable 12 is rotated too much withrespect to the connector assembly. It will be appreciated that cableclamp 36 and clamp ring 38 may need to define their own keyways 53allowing this projection to pass as boot 46 is moved into position.

One skilled in the art will appreciate that embodiments of the presentinvention offer various advantages in comparison with the prior art. Forexample, a connector assembly as described above achieve the followingadvantages:

-   -   1. The new design allows for adding connectors in the field. The        cable is used most efficiently by cutting to the specific length        needed for any given deployment.    -   2. The new design provides for field termination, thus        eliminating the need to store slack cable at the premises. Field        termination removes the need to order cables in advance of        deployment and reduces the need to inventory various lengths of        pre-terminated drop assemblies.    -   3. Cable clamp method sufficient retention for field deployments        and is craft friendly for ease of installation.    -   4. Split stop ring provides for easy assembly.    -   5. Adjustment of the connector orientation provides for torque        free installation allowing cable to maintain optimum coil        configuration.

The following prior art patents are incorporated fully herein byreference in their entireties for all purposes: U.S. Pat. Nos.8,467,653, 8,408,811, and 7,090,407.

While preferred embodiments of the invention have been shown anddescribed, modifications and variations may be made thereto by those ofordinary skill in the art without departing from the spirit and scope ofthe present invention. In addition, it should be understood that aspectsof the various embodiments may be interchanged both in whole or in part.Furthermore, those of ordinary skill in the art will appreciate that theforegoing description is by way of example only, and is not intended tobe limitative of the invention.

What is claimed is:
 1. A connector assembly for a fiber optic cable,said connector assembly comprising: a multi-part inner housing adaptedto support an optical fiber splice connection structure; a cable clamplocated at a proximal end of said inner housing and partially disposedwithin said inner housing, said cable clamp comprising at least onebeam, said cable clamp adapted to engage an outer sheath of a fiberoptic cable, said cable clamp being rotatable with respect to said innerhousing, wherein said cable clamp is axially movable with respect tosaid inner housing over a limited axial extent, and wherein said cableclamp includes first and second spaced-apart flanges which limit theaxial movement of said cable clamp with respect to said inner housing;and a clamp ring separate from and exterior the inner housing andengageable with the cable clamp.
 2. A connector assembly as set forth inclaim 1, wherein said at least one beam defines a plurality of grippingstructures on an inside surface thereof.
 3. A connector assembly as setforth in claim 1, wherein said at least one beam defines a ramp which isurged into engagement with said fiber optic cable by a complementaryramp.
 4. A connector assembly as set forth in claim 3, wherein saidcomplementary ramp is defined in said clamp ring.
 5. A connectorassembly as set forth in claim 4, wherein said clamp ring is configuredto be moved axially into interlocking engagement with said cable clampwhile urging said at least one beam into engagement with said fiberoptic cable.
 6. A connector assembly as set forth in claim 1, whereinsaid cable clamp defines an axial slot for receipt of said fiber opticcable.
 7. A connector assembly as set forth in claim 1, wherein saidoptical splice connection structure includes a splice protection sleevehaving an optical connector ferrule located at one end thereof.
 8. Aconnector assembly as set forth in claim 7, wherein said inner housingdefines an elongate stem at a distal end thereof configured to supportsaid protection sleeve.
 9. A connector assembly as set forth in claim 8,wherein said inner housing comprises two semicircular halves which matetogether.
 10. A connector assembly as set forth in claim 1, furthercomprising an outer boot received over a portion of said inner housing,said cable clamp being contained in said outer boot.
 11. A connectorassembly as set forth in claim 10, wherein said outer boot comprises aninwardly-directed projection which limits rotation of said cable clampwith respect to said inner housing to a predetermined angular extent.12. A connector assembly for a fiber optic cable, said connectorassembly comprising: an inner housing having an elongate stem at adistal end thereof said elongate stem configured to support a protectionsleeve of an optical fiber splice connection structure; a cable clamplocated at a proximal end of said inner housing and partially disposedwithin said inner housing, said cable clamp comprising at least onebeam, said cable clamp being rotatable with respect to said innerhousing; a clamping element separate from and exterior to the innerhousing and adapted to be moved axially into interlocking engagementwith said cable clamp to tighten said cable clamp with respect to saidfiber optic cable; and an outer boot received over a portion of saidinner housing, said cable clamp being contained in said outer boot,wherein said outer boot comprises an inwardly-directed projection whichlimits rotation of said cable clamp with respect to said inner housingto a predetermined angular extent.
 13. A connector assembly as set forthin claim 12, wherein said at least one beam defines a plurality ofgripping structures on an inside surface thereof.
 14. A connectorassembly as set forth in claim 13, wherein said at least one beamdefines a ramp which is urged into engagement with said fiber opticcable by a complementary ramp on an inner surface of said clampingelement.
 15. A connector assembly as set forth in claim 14, wherein saidclamping element is configured as a clamp ring.
 16. A connector assemblyas set forth in claim 12, wherein said cable clamp defines an axial slotfor receipt of said fiber optic cable.
 17. A connector assembly as setforth in claim 12, wherein said cable clamp is axially movable withrespect to said inner housing over a limited axial extent.
 18. Aconnector assembly as set forth in claim 17, wherein said cable clampincludes first and second spaced-apart flanges which limit the axialmovement of said cable clamp with respect to said inner housing.
 19. Aconnector assembly as set forth in claim 12, wherein said optical spliceconnection structure an optical connector ferrule located at one end ofsaid protection sleeve, said ferrule being movable against a springtoward said inner housing.
 20. A connector assembly as set forth inclaim 12, wherein said inner housing comprises two semicircular halveswhich mate together.
 21. A connector assembly fora fiber optic cable,said connector assembly comprising: an inner housing having an elongatestem at a distal end thereof, said elongate stem configured to support aprotection sleeve of an optical fiber splice connection structure; acable clamp located at a proximal end of said inner housing andpartially disposed within said inner housing, said cable clampcomprising at least one beam, said cable clamp being axially movablewith respect to said inner housing over a limited axial extent, whereinsaid cable clamp includes first and second spaced-apart flanges whichlimit the axial movement of said cable clamp with respect to said innerhousing; and a clamping element separate from and exterior to the innerhousing and adapted to be moved axially into interlocking engagementwith said cable clamp to tighten said cable clamp with respect to saidfiber optic cable.
 22. A connector assembly as set forth in claim 21,wherein said at least one beam defines a plurality of grippingstructures on an inside surface thereof.
 23. A connector assembly as setforth in claim 22, wherein said at least one beam defines a ramp whichis urged into engagement with said fiber optic cable by a complementaryramp on an inner surface of said clamping element.
 24. A connectorassembly as set forth in claim 23, wherein said clamping element isconfigured as a clamp ring.
 25. A connector assembly as set forth inclaim 21, wherein said inner housing comprises two semicircular halveswhich mate together.
 26. A connector assembly as set forth in claim 21,further comprising an outer boot received over a portion of said innerhousing, said cable clamp being contained in said outer boot.
 27. Amethod of attaching a fiber optic connector, said method comprisingsteps of: preparing an optical fiber cable for attachment of saidconnector including exposing a predetermined length of optical fiber;attaching a splice protection sleeve and connector ferrule to a distalend of said optical fiber; fixing a cable clamp on said fiber opticcable at a location spaced apart from said splice protection sleeve andferrule; assembling a multi-part inner housing around said optical fiberso as to support said protection sleeve and retain said cable clamp,wherein said cable clamp is partially disposed within said innerhousing, said cable clamp comprising at least one beam, said cable clampbeing rotatable with respect to said inner housing; engaging a clampring with the cable clamp, the clamp ring separate from and exterior tothe inner housing; and moving an outer boot into position such that aportion of said inner housing is received in said outer boot and saidcable clamp is fully contained in said outer boot, wherein said outerboot comprises an inwardly-directed projection which limits rotation ofsaid cable clamp with respect to said inner housing to a predeterminedangular extent.